Blood test detects Alzheimer’s plaques building up in brain

A blood test can detect whether plaques of beta-amyloid are building up in a person’s brain – a sign that they may develop Alzheimer’s disease.

People with Alzheimer’s disease tend to have sticky clumps of beta-amyloid in their brains, although the part these plaques play in the condition is unclear. Until now, the only way to monitor plaque build-up in a person’s brain has been through expensive PET-scans, or by performing an invasive spinal tap procedure.

Now a team has developed a simple blood test that may make it possible for family doctors to screen for Alzheimer’s risk during health check-ups. “This kind of test could be used to screen many thousands of patients to identify those at risk for Alzheimer’s disease, and to start treatments before memory loss and brain damage,” says Randall Bateman, of Washington University in St Louis, who unveiled the test at the Alzheimer’s Association International Conference in London today.

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Bateman says the test could be used in a similar way to annual checks on cholesterol. The test works by measuring the relative amounts of different forms of beta-amyloid, a sign of whether plaques are likely to be building in a person’s brain. They developed the test by comparing ratios of beta-amyloid types in 41 people’s blood with PET scans showing how much beta-amyloid had aggregated in their brains.

Early detection

The hunt for a drug that can effectively treat Alzheimer’s disease continues, but in the meantime, evidence is growing that healthy lifestyle interventions – such as exercise and healthy diet – can reduce the risk of developing the disease by as much as 30 per cent. In theory, the blood test could reassure some people that they are not at risk of developing the condition, while identifying others who might benefit from further tests and lifestyle changes.

Amyloid plaques start developing 15 to 20 years before the symptoms of Alzheimer’s disease start to show, and testing positive wouldn’t mean that a person is definitely going to develop the condition.

“I’m very positive about the test, but would like to see it validated,” says Dean Hartley of the Alzheimer’s Association. “It was a very small sample, and they’re trying to confirm it in an additional 180 people.”

“But in time, if we can get a blood test, it will take us further, just as cholesterol tests did in the cardiovascular field,” says Hartley.